The present invention relates to systems for monitoring the operation of a boom. In particular, the present invention relates to a system for monitoring operation of a boom in which loads on the boom's actuator assemblies are sensed, information based upon the sensed loads is stored, and an output is provided based upon the stored information which is indicative of potential causes of boom failure.
Booms have one or more boom sections which are typically used to lift a load or reach to a particular distant location. Each boom section has a corresponding actuator assembly which supports the boom section as well as any load supported by that boom section. Typically, the actuator assemblies are hydraulic piston/cylinder assemblies. The load supported by individual actuator assemblies and corresponding boom sections, as well as the load caused by the weight of the boom itself, is monitored. The maximum loads that the actuator assemblies and/or boom sections are structurally designed to withstand are generally known by the boom manufacturer. This information may be translated to maximum loads that each of the boom's actuator assemblies and corresponding boom sections can support without exceeding design limitations.
Booms are frequently subjected to work conditions in which loads supported by the boom exceed design limitations. These excessive conditions can be caused for example by lifting excessive loads, by attempting to extend the boom while a section of the boom is pinned against a wall or other obstacle and by a foreign object such as a separate piece of machinery falling on a section of the boom. Abuses such as these occur in construction applications on a daily basis. Frequently, the result is shortened boom life and/or the failure of one or more boom sections or actuator assemblies.
A very common problem experienced by boom manufacturers is that customers frequently deny that a failed boom was subjected to abusive conditions. In lawsuits in which someone was injured by a cracked boom or a boom which has tipped over, boom manufacturers frequently find it difficult to prove that the failure was caused by abuse, and not by a defect in the boom. Also, frequent abuse of booms makes it difficult for boom manufacturers to offer warranties to their customers. Fixing or replacing boom components which have failed as a result of being subjected to excessive loads, as opposed to being the result of manufacturing defects, is typically cost prohibitive.
Even if a boom is not subjected to loads which exceed design limitations, boom components may still experience fatigue failure because of the repetitious nature of boom movements under loaded conditions. Because fatigue failure is dependent upon the total number of cycles experienced by the boom components, and because the manufacturer has no way to determine how many cycles a particular user will put the boom through in a given period of time, predicting when boom components will experience fatigue failure is extremely difficult.